This is a proposal for studies on idiopathic ulcerative colitis and spontaneous large intestinal carcinoma in a promising new animal model. The animal is the cotton-top tamarin (Saguinus oedipus), which is a small South American monkey that has been discovered recently to suffer from colon cancer in association with chronic, non-infectious colitis. It is the only known animal, besides humans, in which ulcerative colitis is associated with a high incidence of cancer. The investigative work would center on The Ohio State University colony of cotton-top tamarin which is one of the three or four colonies of these animals in the Unites States. These tamarins will be experimental controls in parallel comparative studies on wild tamarins. Urgency of the work is related to these animals being on the world lid\st of endangered species and the danger of extinction of the most likely model for providing the clues to understanding of two significant human diseases. This proposal is directed to the major aim of identifying the etiologic factors involved cotton-top tamarin. The project will determine if spontaneous colitis and cancer occur in tamarins living in their jungle habitat or if the diseases are manifestations of captivity. Preliminary field studies in animals and that unidentified conditions in captivity might be precipitating factors. The methods will involve endoscopic examination and biopsy of the colon and will not harm the animals in any way. Wild tamarins will be captured, examined and released, unharmed, back into their native habitat. Specific aims of the project are to: (1) Document the development and progression of colitis and cancer in the Ohio State colony; (2) Determine the incidence and severity of colitis and cancer in feral tamarins; (3) Determine if captivity is the precipitating factor is development of colitis and the cancer sequel; (4) Determine if cold environmental temperatures are stress factors in captivity; (5) Determine if humoral indicators of stress are elevated in captive relative to feral animals.